In electronic systems, each subsystem may have its own voltage-level requirement that differs from that supplied by the system's power source. For example, different subsystems in a locomotive may operate on direct current (“DC”) at different voltage levels. DC-to-DC converters (“DC-DC converters”) allow a single source to power multiple subsystems operating at different voltage levels.
Traditionally, switch-mode converters are generally preferred over other types because they are capable of producing an output voltage higher than the input voltage and are capable of bidirectional operation at a higher efficiency than linear converters. However, switch-mode converters have their own limitations. For example, the conversion speed is limited by the switching frequency of the transistors comprising the converter. Furthermore, switching losses resulting from the resistance of each transistor may decrease the efficiency of the converter. Additionally, while DC-DC converters operate by temporarily storing energy in their transistors, these converters do not provide a means of storing energy for any significant amount of time if, for example, the load on the output of the converter shuts down for a period of time.
One solution for power conversion is described in U.S. Patent Application Publication No. US 2011/0050174 A1 (“the '174 publication”). The '174 publication is directed to an apparatus for transferring energy using onboard power electronics. The apparatus includes a bidirectional DC-DC voltage converter coupled to an energy storage device. The apparatus also includes a controller configured to control the bidirectional DC-DC converter to convert a first charging energy on a voltage bus into a second charging energy suitable for charging the energy storage device during a charging operation and to monitor a voltage of the energy storage device during the charging operation.
Although the system disclosed in the '174 publication may be capable of transferring energy to transient or pulsed loads, the solution disclosed in the '174 publication may still suffer from a number of possible drawbacks. For example, the DC-DC converters of the '174 publication require transistors and are thus subject to the same conversion rate and efficiency limitations discussed above. Additionally, the apparatus the '174 publication discloses can store energy on the input side of the converter, where the energy storage device connects to the converter, but not within the converter itself.
The presently disclosed systems and methods may mitigate or overcome one or more of the above-noted drawbacks and/or other problems in the art.